The so-called solid-electrolyte interface (SEI) derived from the interaction between electrolyte and electrode plays a decisive role in Li-ion battery performance. Lithium difluoro(bisoxalato) phosphate (LiDFBOP) as the derivative of LiPF6 has caused great attention among the researchers. However, the mechanism of effect for LiDFBOP salt has not yet revealed, which limits the findings for the fundamental cause of performance improvement. In this work, the effect of LiDFBOP on the mesocarbon microbead (MCMB) anode electrode has been investigated with aid of surface analysis technique, such as scanning electron microscope (SEM), X-ray photoelectron spectrum (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). On the basis of the modification with LiDFBOP, the long-term cycling and degradation resistance of Li/MCMB half cells have been achieved, which results from the preferential decomposition of LiDFBOP regulating the decomposition law of the electrolyte system. The SEI film with layer structure has different composition distribution under the obstruction of LiDFBOP of the decomposition of LiPF6. The more organic ingredients are distributed in the SEI film on the electrolyte side, which leads to low impedance and fast transportation of lithium ions. The special ingredient distribution is ascribed to the obstruction of LiDFBOP on the decomposition of LiPF6. This work signifies the research of the effect of SEI film distribution on the battery performance.

In this study, a novel three-dimensional (3D) [email protected](OH)2 nanorod array (NRA) photoanode with a type-II band alignment and a p-n junction has been designed and constructed via a simple electrochemical deposition of hierarchical β-Ni(OH)2 nanosheets onto the surfaces of the CdS NRAs. The 3D [email protected](OH)2 NRA photoanode fabricated under the optimal deposition current exhibits remarkably improved photoelectrochemical water splitting performance, and obtains a photocurrent density of up to 1.1 mA/cm2, 5-fold that of the pure CdS NRA photoanode. Most importantly, the solar-to-hydrogen conversion efficiency of the 3D [email protected](OH)2 NRA photoanode is 3.3-fold higher than that of the pure CdS NRA photoanode at 0.67 V vs. RHE. The electrochemical and photoluminescence emission measurements confirm that the enhanced PEC water splitting capability of the prepared 3D [email protected](OH)2 NRA photoanode is attributed to the efficient charge separation, which is achieved by the synergistic action of the type-II energy alignment and the p-n junction.

Results are presented of canonical ensemble Monte Carlo simulations of molten salt electrical double layers. Electrode surface atoms and ions are modelled as soft spheres with the use of the Lennard-Jones potential. Ions and electrode atoms have the same diameter but differ in the applied energetic Lennard-Jones parameter values. The electrode surface consists of C (graphite), Hg or Pb atoms. The values of the applied parameters allow a comparison of the results obtained with those of real systems. The paper presents such results as: ion distributions, the mean electrostatic potential and differential capacitance. The differential capacitance values are collated with theoretical and experimental results. The capacitance curves obtained by simulations are flatter than experimental ones. The theoretical capacitance values, in contrast to the experimental ones, are smaller at the positive electrode potentials and this difference is due to the occurrence of chemical bonding between anions and electrode surface in experimental systems.

pH electrodes exhibited wide applications in the fields of food science, environmental science, and bioanalytical analysis. In this work, we demonstrate the facile fabrication of silver-antimony (Ag–Sb) binary alloy electrodes through a one-step melt casting method. XRD, SEM and EDS were used to characterize the alloy electrodes. The response mechanism of the pH electrode was studied by Tafel plots, which clarified the role of metal (Sb) and metal oxide (SbOads) in the pH response process. The corrosion resistance of the alloy electrode was researched by electrochemical impedance spectroscopy (EIS), which proved the advantages of the Ag–Sb alloy electrodes. In addition, our Ag–Sb pH electrodes exhibited promising sensing performance with the near-Nernstian response sensitivity is 54.6 mV/pH. The other performances including response time, stability, reversibility, hysteresis, and temperature coefficient, also demonstrated that the Ag–Sb binary alloy electrodes have good pH speciality, and it will potential applications for environmental monitoring in situ. These research results can complement and perfect the theoretical basis of metal/metal oxide pH electrodes, thus guiding the preparation of metal/metal oxide pH electrodes and promoting the exact and extensive application of metal/metal electrodes in more aspects.

Nitrogen doping was widely used to increase the electronic density of carbon materials and to enhance the adsorption of the supported metal catalysts. However, the exact interaction between various doped nitrogen species and palladium (Pd) have rarely been reported for formic acid oxidation (FAO). In this study, the effect of the doped pyridinic-N and pyrrolic-N on the electronic structure and the electrochemical activity of Pd toward FAO are investigated. The oxidation state of Pd is reduced and more metallic Pd is formed when Pd nanoparticles supported on pyridinic-N and pyrrolic-N doped carbon materials. Density functional theory (DFT) calculations simulate that the adsorption energy of HCOO* and *COOH on Pd/pyrrolic-N are lower than those on Pd/pyridinic-N. Both DFT and electrochemical measurements suggest that the FAO activity of Pd is more correlated with the pyrrolic-N than pyridinic-N. The catalyst contains more pyrrolic-N species exhibits higher electrochemical activity and faster kinetics for FAO reaction. Moreover, Pd2+-N complexes are formed in all the nitrogen doped catalysts and display good activity for FAO. In this study, Pd supported on urea treated carbon (Pd/UR) owns the highest content of pyrrolic-N and exhibits the best activity for FAO.

Effect of tetraethylammonium tetrafluoroborate (TEABF4) additives on the charge and discharge properties and gas formation in dual ion battery using graphitic carbon and Li4Ti5O12 for positive and negative electrode, respectively was investigated. Although cycle stability was poor and large amount of gas was formed in dual ion battery using LiPF6 for a support salt, it was found that the reversibility of charge and discharge and cycle stability was much increased by addition of TEABF4. By using LiPF6 + TEABF4 in dimethyl carbonate (DMC)-methyl ethyl carbonate (MEC)-propylene carbonate (PC) (1:1:1), discharge capacity of 60 % of initial capacity was sustained after 1,017 cycles with 99% coulomb efficiency and negligible amount of gas was formed. These positive effects of TEABF4 addition were assigned to the suppression of side reaction on electrode, in particular, at Li4Ti5O12 negative electrode. Lewis acidity in electrolyte seems to be related with electrolyte decomposition and decreased cycle stability was caused by the unbalanced capacity of interaction between positive and negative electrode.

The discrepancy reported in the literature between interdigitated electrode cell constants obtained from experiment and those obtained from numerical simulation is attributed, in part, to geometry-induced frequency dispersion. The frequency dispersion associated with the interdigitated electrode geometry yields a complex ohmic impedance with real asymptotic limits for ohmic resistance at high and low frequencies. The determination of cell constants from impedance measurements performed on gold interdigitated electrodes in aqueous KCl solutions of differing electrolyte resistivity is shown to be confounded by the presence of a surface film and by extrapolated values that fell between the high- and low-frequency ohmic resistances. A method is presented to ensure that impedance measurements performed in aqueous KCl solutions of differing concentration yields the low-frequency ohmic resistance, from which a well-defined cell constant is obtained that agrees with numerical simulations. The experimental results are supported by finite-element simulations that accounted for the presence of a film.

Electrochemical impedance spectroscopy (EIS) applied for aptasensing is being extensively studied for a variety of targets. Substitution of a symmetric electrode configuration for a conventional three-electrode setup on EIS aptasensing is becoming a trend due to its simple and favorable characteristics for biochip fabrication. However, a single Randles circuit is often used for impedance element parameter fitting in symmetric electrode aptasensing without rationalized basis of validity to date. In this work, an AC impedance model is derived for proving the validity of simplifying a symmetric Randles circuits in series into a single one and is examined with aptasensing applications. With the model, circuit parameter relationships can be quantified and correlated between symmetric and three-electrode configurations. The relationships are verified by comparing the fitted parameters obtained from standard gold electrodes (SGEs), microfabricated symmetric Au electrodes, and interdigitated array (IDA) Au electrode chips with different surface and detection conditions. The model is then found valid for different redox species composition (either Fe(CN)63− or Fe(CN)63−/4- is used) and for both blank and aptamer modified surfaces. From aptasensing of thrombin and tumor marker mucin 1 (MUC1), it is proved that the measured dissociation constants (KD: 129.4 nM for thrombin and 16.3 nM for MUC1) remain the same between a symmetric and three-electrode configuration, but the maximum change of charge transfer resistance (Bmax) is doubled in the symmetric one. This means that the symmetric configuration not only yields the same KD, but also results in a doubled binding signal for EIS aptasensing. In addition to the model derivation and experimental validation, specific EIS aptasensing of MUC1 using a symmetric electrode configuration is successfully demonstrated in this work.

The precise ion determination at solid-liquid interfaces and the underlying mechanisms behind this are of paramount relevance in a wide range of technological, environmental and biological applications. In this work, a systematic exploration into the behavior of monovalent salts in an extended nanospace is performed with Monte Carlo simulations in an attempt to provide a more general description. We obtain rather useful information not only on the lateral organization of ions in the Stern layer region but also on their distribution in the direction normal to the interface. Our simulation results show a remarkably consistent picture with the experimentally observed Stern layer structure in the discrete surface charge representation. It is recognized that sensitive to the radii of hydrated counterions and the solution dielectric response, their binding to low-dielectric interface sites forming a set of Bjerrum pairs is crucially driven by electrostatics. Also, we evaluate the validity of the uniform surface charge modeling that underlies previous theories and numerical simulations in predicting the structural properties of monovalent salts under confinement.

Introducing oxygenated functionalities into carbon networks can provide additional pseudocapacitance for supercapacitors. However, excessive and unstable oxygen functional groups usually cause low electrical conductivity and rate performance. Herein, we propose a novel and simple strategy for tunable functionalization of edge-enriched graphene nanoribbons by means of dielectric barrier discharge (DBD) plasma. The functionalized graphene nanoribbons from DBD plasma exhibit high specific capacitance owing to the suitable oxygen functional groups and the intrinsic edge-enriched structure. The assembled symmetric supercapacitor device based on as-prepared graphene nanoribbons with oxygenated functionalities exhibits a superior energy density of 12.65 Wh kg−1, and 93.76% capacitance retention after 10,000 cycles in 1 M Na2SO4 aqueous electrolyte. This work may find a new way to finely control functionalities on carbon nanomaterials for high-performance energy storage devices.

Efficient utilization of sulfur atom in MoS2-based electrocatalysts on the basal plane is highly desirable and expectable to optimize the electrocatalytic performance for hydrogen evolution reaction (HER). Herein, removing atoms on the basal plane of layered MoS2 by Li-ion intercalation leading to extraordinarily enhanced electrocatalytic performance is newly reported, which provides a novel way to active the basal planes of layered transition metal sulfides towards hydrogen evolution. It is found that the desulfurization of layered MoS2 can bring atomic vacancies on the basal plane, which is confirmed to be active sites towards hydrogen evolution experimentally and theoretically. The first-principle calculations reveal that the desulfurization induced atomic vacancies not only reduce the free energy of hydrogen adsorption (ΔGH*), but also accelerate the electron transfer on the basal plane. Besides, the phase transformation from 2H to 1T during the electrochemical lithium-ion intercalation could reach higher electronic conductivity, thus further optimize the HER kinetics through phase engineering. For these reasons, the desulfurized MoS2 displays improved HER activity with lowered overpotential of 200 mV to obtain 10 mA cm−2, high stability, decreased Tafel slope of 65 mV dec−1 and enhanced TOF of 0.093H2 s−1 at overpotential of 250 mV, which are much better than that of the pristine MoS2 and other optimized MoS2-based catalysts.

Optimizing the ratio of transition metal (TM) ions is an effective modification strategy to improve the electrochemical properties of LiNi0.5+xCo0.2+yMn0.3+zO2 (x+y+z=0, and the absolute values of x, y and z are not more than 0.03). In this work, we develope a new method which combines the simplex method with the normalization method of evaluation index (SNEI) to optimize the TM ion ratio of LiNi0.5+xCo0.2+yMn0.3+zO2. This method can significantly improve the optimization efficiency. Only after three times of simplex operation, the optimum component of LiNi0.493Co0.214Mn0.293O2 is obtained. The results show that the electrochemical properties of material have improved significantly through adjustment of the ratio of TM ions slightly, and LiNi0.493Co0.214Mn0.293O2-based cells exhibit long cycle life and good rate capability due to the low degree of Li/Ni mixing and the slow increase of impedance during cycling. Simultaneously, the impact of the intensity of the TM ion ratio on electrochemical performances are studied, and the following trend is observed in decreasing the sensitivity of the evaluation indexes: cycle performance > rate capacity > specific capacity. This newly-developed SNEI method has a wide applicability and great prospects in electrolyte and electrode formulations.

The present contribution is intended to provide an in depth approximation to the role plaid by the thick passive layers formed over years in atmospheric exposure in the electrochemical response of steel embedded in concrete. This information is expected to be of general interest for the interpretation of electrochemical data as the corrosion potential and the polarization resistance, commonly employed for assessing steel corrosion in this system. Results for blank samples and samples containing chlorides are discussed based on findings from electrochemical impedance spectroscopy. Temperature was considered in the study as a parameter for acting on both the chemistry of the pore electrolyte and the specific volume of the oxides layer. By this approach, we were able to identify the contribution of the oxides layer to the impedance spectra in the 10 kHz-1 Hz frequency range. Kinetic information for corrosion rate can be obtained in the low frequency region of the impedance spectrum. The polarization resistance, the DC resistance value, has to be corrected for the impedance at about 1 Hz. The oxides layer supports the oxygen cathodic reaction, but also the anodic and cathodic processes corresponding to the re-oxidation and reduction of the layer itself. Compared to layers formed in the absence of chlorides, the presence of chlorides in the concrete mix leads to the formation of a more oxidised oxide layer, with decreased redox activity and more prone to cracking under thermal cycling. Thus, the presence of chlorides decreases the corrosion protective property of the oxide layer.

1D vanadium pentoxide materials have been extensively studied because of their fascinating properties and versatile applications. If they could be manufactured on a large scale, 1D V2O5 materials would be attractive for more commercial applications. In this work, we report a novel rapid-heating-assisted polymerization strategy to prepare 1D V2O5/PEDOT core-shell nanobelts. By rapid heating the freeze-dried V2O5 hydrogel, we can immediately obtain large quantities of uniform V2O5 nanobelts with high purity. After coating an ultrathin PEDOT skin, the resultant 1D V2O5/PEDOT core-shell cathode exhibits excellent rate performance and superior cycling stability, as compared to the commercial V2O5 powders. We present an important approach toward mass-producing 1D V2O5 nanomaterials and can be extended to preparing other 1D materials for potential applications ranging from electronics to energy conversion and storage.

Bismuth-based electrodes have been proved the most reliable replacement of highly toxic mercury for the anodic stripping (AS) and cathodic voltammetric determination of metal ions and organic compounds, respectively. Herein, we report for the first time on the implementation of two-dimensional (2D) bismuth, it called “bismuthene”, for the AS voltammetric determination of Pb(II) and Cd(II) ions. Bulk bismuth was exfoliated by a facile and fast shear-force liquid phase exfoliation method. Exfoliated bismuthene layers were characterized by means of SEM, EDX, Raman, FT-IR, electrochemical impedance spectroscopy and cyclic voltammetry. Bismuthene colloids were mixed with dispersions of few-layer graphene, which was used as supporting material in order to achieve the desired adherence of bismuthene films onto the surface of glassy carbon electrode (GCE) as well as an effective electrical communication between them and with the electrode surface. The optimum loading of bismuthene in the bismuthene/graphene composite (2D-Bi/Gra) was investigated, while other parameters such as the deposition time and deposition potential were also examined. Under selected conditions and for a 3 min preconcentration time, the limit of detection (S/N 3) of each target ion was 0.3 μg L−1. 2D-Bi/Gra/GCEs were successfully applied to the determination of Pb and Cd in tap water samples in the presence of potassium hexacyanoferrate(II) for the alleviation of copper interference. Results suggest that 2D bismuthene/graphene modified electrodes offer great promise for the determination of sub-microgram per liter Pb and Cd and could contribute greatly in heavy metal ions and other organic compounds sensing applications.

Extraction of photosynthetic electron for bioelectrical energy harvesting is an efficient approach to utilize solar energy harvested by photosynthetic microorganisms. To explore this approach in natural and artificial photosynthetic system in which alga and photosynthetic bacteria are usually coexisted, the intracellular electron extraction from mixed photosynthetic consortium of Chlorella vulgaris and Rhodopseudomonas palustris was investigated under three-electrode mode by holding working electrode at different potentials. The mixed-culture biofilm grown at 0 V exhibited a maximum Coulomb efficiency of 42.12% while the peak current (12.2 mA) was 8.07, 1.5, 2.97 and 4.65 fold higher than that produced at −0.4 (1.5 mA), −0.2 (8.06 mA), 0.2 (4.08 mA) and 0.4 V (2.6 mA), respectively. The electrode potential can regulate the dominant species within the biofilm. Large enrichment of Rhodopseudomonas palustris in the biofilm was responsible for the high photosynthetic electron extraction efficiency at 0 V since the photosynthetic electrons extracted by the electrode were mainly derived from photoheterotrophic metabolism of Rhodopseudomonas palustris. Extraction of equivalent amounts of intracellular electron from Chlorella vulgaris required higher potential than that from Rhodopseudomonas palustris and was highly dependent on the presence of exogenous electron mediator. As an electron sacrificer, photosynthetic oxygen released by Chlorella vulgaris could complete electron with electrode. Intracellular electrons can also be extracted from dark respiration, but the peak current (6.4 mA) was 47.54% lower than that produced under illumination (12.2 mA) due to low exoelectrogenic activity of biofilm.

High nickel LiNi0.8Co0.15Al0.05O2 (NCA) cathode material has become one of the most promising cathode materials in the field of power batteries, but the side reaction between the conventional LiPF6-based electrolyte and the surface of the NCA material results in poor material interface stability. In this work, a compatible lithium difluoro(oxalate)borate (LiDFOB)-based electrolyte by the employment of sulfolane (SL) as a representative sulfur-containing solvent has been built to enhance the interfacial stability of NCA electrode. The composition, morphology and electrochemical properties are studied by X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy et al. Results show that the decomposition of LiDFOB on the surface of the positive electrode material contributes to forming a uniform cathode electrolyte interface (CEI) film, which subsequently reduces the dissolution of metal ions and hinders the structure transition of the material from the layered structure to spinel or rock-salt phases. Besides, the sulfur-containing products resulted from the decomposition of SL promote the conductivity of Li+ ions for CEI film, which makes up for shortcomings of LiDFOB. Moreover, more LiF has been formed due to the synergistic action between LiDFOB salt and SL solvent, improving the stability and density of CEI film, reducing the thickness of CEI film, and further improving the cycle performance of the battery.

Poor stability restricts the use of polyaniline as a transition-metal-free, high-capacity electrode material for electrochemical energy storage. To improve the durability, methods such as adding a carbonaceous support and thermal treatments have been suggested. Here, we combine both of these approaches and study their effects on the degradation of a composite of polyaniline and acid-treated multi-walled carbon nanotubes (PANI/a-MWNT) when used as a positive electrode in a lithium-ion cell. The composite is prepared through facile ultrasonic-assisted mixing of aqueous colloids, processed into binder-free electrodes and heat treated under vacuum (120–180 °C). PANI without the carbon support presents a poor cycling stability due to a decreasing conductivity and changes in the particle morphology. The a-MWNTs are shown to inhibit these changes and to enhance the electrochemical accessibility of PANI in the composite. The heat treatment, in turn, improves the stability of the composite during open circuit conditions, which is ascribed to cross-linking of the polymer. However, with prolonged cycling, the stabilizing effect is lost. Analysis of the electrodes after the cycling reveals that both the pristine and the heat-treated composite undergo dedoping and side reactions with the electrolyte. The extent of the changes is larger for the pristine composite.

Although the peculiarities of electrodeposition in the preparation of metal hydroxides is quite attractive, adequate interpretation of this process still lacks. Here, a novel interpretation of the electrodeposition of nickel cobalt double layered hydroxides (NiCo-LDHs) is proposed. Different from the traditional strategies implemented in the pure nitrate or nitrate-assisted electrolytic baths, the sulfate solution with thiourea (TU) additive is used. Benefited from the chelating and inducing effects of TU, honeycomb-shaped NiCo-LDH nanosheets can be successfully electrodeposited on nickel foam (NF). When performed as free-standing electrodes, these integrated electrodes show a robust capacitive performance. Specifically, NC2S12-15/NF (deposition for 15 min) electrode can deliver remarkable electrochemical properties, such as large capacity (1198 F g−1 at 1 A g−1), excellent rate performance (1000 F g−1 at 100 A g−1) and good cycling stability. Additionally, the NC2S12-15/NF//activated carbon (AC) hybrid capacitor (HC) can sustain extraordinary cycle life (88.3% retention for 10,000 cycles) and high energy density (29.1 Wh kg−1), further demonstrating the qualified capacitive behavior of NC2S12-15/NF electrode. This work provides a new insight into the electrodeposition of metal LDHs based on the design of the electrolyte solution.

Blending two materials together to improve electrode performance has been proven an effective and practical strategy in the battery industry. Herein, we fabricate a novel n-HC/GeP5 composite that doubles the energy density over hard carbon (HC) without sacrificing cycle stability and rate performance. The GeP5, with high capacity (2289 mAh g−1), ultra-high conductivity (2.4*106 S m−1) and high initial coulombic efficiency (ICE > 90%), enables it serve as an effective additive to HC at a low weight percent. By introducing 20% wt GeP5 by mass ratio into HC, the obtained n-HC/GeP5-20%wt composite improves the reversible capacity from 400 mAh g−1 to 898 mAh g−1, and improves ICE from 74% to 85%. In addition, the rate capability of n-HC/GeP5, with 516 mAh g−1 and 64% retention comparing 1C–8C, is much better than that of pure HC (273 mAh g−1, 54% retention). Consequently, when tested at 1C and 8C for 550 cycles, large reversible capacity of 575 mAh g−1 and 400 mAh g−1 respectively can still be obtained for this n-HC/GeP5-20% hybrid, revealing its great potential to be used in commercial battery products.

RuO2 is commercially employed as an anode catalyst in the chlor-alkali process. It is also one of the most active electrocatalysts for the oxidation of water, relevant to electrochemical water splitting. However, the use of RuO2 is limited by its low anodic stability under acidic conditions, especially at high overpotentials. In the present work, the electrochemical stability of model RuO2(110)/Ru(0001) anodes was investigated in order to gain a deeper understanding of the relation between structure and performance in Cl2 and O2 evolution reactions (CER and OER, respectively). Online electrochemical mass spectrometry was used to determine the onset potential of CER and OER in HCl and H2SO4 electrolytes, respectively. The onset potential of OER was higher in HCl than in H2SO4 due to competition with the kinetically more favorable CER. A detailed stability evaluation revealed pitting corrosion of the electrode surface with exposure of Ru(0001) metal substrate concomitant with the formation of a hydrous RuO2 in some areas regardless of the applied electrochemical treatment. However, despite local pitting, the RuO2(110) layer preserves its thickness in most areas. Degradation of the electrode was found to be less severe in 0.5 M HCl due to a decrease in the faradaic efficiency of RuO2 oxidation caused by competition with the kinetically more favorable CER.

The practical application of Sn-based anodes are seriously hampered by the dramatic volume expansion (∼300%) during charge/discharge processes, which induces large internal stress that can make the anode materials easily pulverized and cracked to cause the loss of electrical contact and thus severe capacity fading. In order to address this problem, a versatile strategy has been developed for preparing multiple Sn/Cu nanoarrrays including Cu–Sn end-to-end nanowires (NWs), [email protected] core-shell NWs and [email protected] core-shell semi-nanotubes (NTs) through a two-step successive-electrodeposition process with track-etched polycarbonate (PC) membranes as template: metallic Cu nanowire arrays are first electrodeposited inside the nanopores of the PC membrane on the Cu foil substrate, followed by the deposition of Sn in the second step. The architectures of these samples can be readily tuned by modifying the synthesis conditions or by treating the PC membrane with 3-aminopropyl-triethorxysilane (APTES). The distinct structures of these electrodes provide a high performance in lithium ion batteries. The discharge capacity of Cu–Sn NWs, [email protected] NWs, and [email protected] NTs after 400 charge-discharge cycles at a specific current of 0.8 A g−1 is 714, 402, and 1193 mA h g−1, respectively. Such a performance can be attributed to a local confinement effect between Sn and Cu which inhibits the pulverization of the active material, and an alloy/dealloy activation process achieving high reversible capacities.

This paper describes electrochemical behavior and an electrooxidative method for the determination of diclofenac, DF, (2-[(2,6-dichlorophenyl)amino]benzene-acetic acid) and acetaminophen, AC, (N-acetyl-p-aminophenol). Drugs electrochemical oxidation was realized on the surface of graphite-based screen printed electrodes (SPE) modified with a stable dispersion of multiwalled carbon nanotubes (MWCNTs) in aqueous solutions of an amphiphilic poly(1,2-butadiene)-block-poly(2-(N,N-dimethylamino)ethyl methacrylate) diblock copolymer (PB-b-PDMAEMA). The oxidation peak potentials of DF and AC were detected at + 0.53 ± 0.02 V and 0.35 ± 0.02 V (vs. Ag/AgCl), respectively. The analytical characteristics of electro-oxidation of the drugs on the SPE/(PB290-b-PDMAEMA240/MWCNT) constructs were estimated with a detection limit of 35 nM and 40 nM, and a sensitivity of 4.90 mA/mol and 2.3 mA/mol for DF and AC, respectively. Electro-oxidation of DF and AC was applied as analytical technique for the detection of theses pharmaceuticals in their mixtures and in human serum. Further, we demonstrate an approach for the estimation of the enzymatic activity of cytochrome P450 3A4 (CYP3A4) based on the electrochemical oxidation of residual DF used as a model drug. Two separate electrochemical cell were used each was supplied by specified electrode. The first one was CYP-sensitive electrode, which contains CYP3A4 immobilized on didodecyldimethylammonium bromide (DDAB) as a CYP3A4 fixing matrix, while another one was newly developed drug-sensitive electrode. Therefore, drug conversion, which takes place in the first electrochemical cell supplied by CYP-sensitive electrode, can be quantitatively monitored by drug-sensitive electrode by taking aliquots at specified time periods and assaying a residual drug concentration in the second electrochemical cell. Thus, the estimation of kinetic parameters for CYP3A4 catalysis can be carried out.

As anodes for solid oxide fuel cells (SOFCs), one of the significant advantages for perovskite alternatives over conventional Ni-based cermets is the high tolerance to sulfur poisoning. However, there are some controversies on sulfur poisoning mechanisms of perovskite anode cells and many related works are not systematic and convincible enough. Herein, with 200 ppm H2S–H2 fed to anode chamber, we find that (La0.8Sr0.2)0.95MnO3-δ/(Sc2O3)0.1(CeO2)0.01(ZrO2)0.89 (LSM/ScSZ) cathode undergoes a severe deactivation using Ceramabond 552 sealant, while La0.8Sr0.2Fe0.9Nb0.1O3-δ (LSFNb) anode keeps activating. Adopting annealing-quenching treatment to simulate in-situ conditions, transmission electron microscopy studies reveal that ∼5 nm hexagonal FeS nanoparticles and ultrathin sulfur species layer are dynamically-formed on LSFNb surface upon exposure to 200 ppm H2S–H2 since they disappear after the subsequent annealing in H2. Finally, sulfur poisoning stages of the cells and the corresponding mechanisms are discussed systematically. Our work offers a new dimension for understanding sulfur poisoning behaviors of whole cells and sulfur poisoning and promotion effects on LSFNb perovskite anode.

Excess PbI2 has been widely introduced in halide perovskite precursor solution to passivate the grain boundary defects in high efficient perovskite solar cells (PSCs). However, the passivation effect is highly sensitive to the PbI2 content and overmuch PbI2 affects the crystalline growth and charge transport. We report here a precious control of excess PbI2 into perovskite grain boundaries by methylamine treatment for efficacious defects passivation and charge extraction. The crystallization of the deposited perovskite films was carefully evaluated and the charge recombination dynamics were systematically analyzed through time-resolved photoluminescence spectroscopy, space charge limited current, electrochemical impedance spectroscopy and Mott-Schottky analysis. The precise PbI2 introduction to the grain boundaries results in a significantly lower defect state density, efficient charge extraction and prolonged carrier lifetime, causing a notable increase of short-circuit current density and negligible hysteresis in the corresponding device. Our work demonstrates a reliable method to alleviate the rigorous tolerance of PbI2 excess in high efficient PSCs.

Carbon materials with favourable porous architecture and heteroatom functionalities are well considered for energy storage applications due to its excellent structural and electrochemical properties. In this paper solid-state symmetric supercapacitor (SC) using heteroatom (nitrogen and oxygen) inherently co-doped microporous carbon (HMC) was investigated. HMC was prepared by simple carbonization method without any additives by adopting multistep experimental procedures. 4, 4′-diamino-diphenyl sulphone (DDS) was pyrolyzed at 950 °C in a single step and HMC with surface area of 1766 m2 g−1 and a total pore volume of 0.87 cm3 g−1 was obtained. The structural characteristics and the content of heteroatom functionalities were manipulated with pyrolysis time to improve the elctrochemical behaviour. The symmetrical SC was fabricated with polyvinyl alcohol (PVA) supported 6 M KOH and 1 M Na2SO4 as gel electrolytes. The performance of solid-state SC showed good cycling stability and high energy density. The device exhibited a maximum energy density of 35 W h kg−1 with a maximum power density of 3180 W kg−1 remained stable (91% capacity retention) after 5000 cycles. Finally, the device using porous carbon electrode material with PVA+1 M Na2SO4 able to light a LED after charging for about 5sec.

Perovskites have been significantly considered as promising materials for electrochemical energy storage in the recent years. Co doping of Mn and Nd with hydrothermally synthesized LaFeO3 (LF) perovskite resulted in La0.8Nd0.2Fe0.8Mn0.2O3 (LNFM) with significantly higher specific capacitance of 158 F/g at 50 mV/s compared to non-doped and single doped LF samples. Subsequently, LNFM/nitrogen-doped graphene oxide (NGO) nanocomposite was prepared and investigated. It was found out that the introducing of NGO substantially enhances the specific capacitance of the nanocomposite up to 1060 F/g at 50 mV/s. Besides, the composite revealed outstanding capacity retention as 92.4% capacity retained after 10000 continuous cycle (85.37% for the LNFM sample). In overall, the electrochemical behavior of the composite with 1:1 ratio of LNFM/NGO confirms its high potential as supercapacitor for energy storage applications.

A facial and efficient process for the synthesis of porous ZnxCo3-xO4 hollow nanoboxes using zeolitic imidazolate frameworks as precursors has been demonstrated in this study, the as-prepared electrodes are applied for both LIBs and SIBs. The porous structure and hollow interspace can not only provide valuable channels and voids for lithium/sodium ion transfer and storage, but also buffer the stress/strain caused by volume changes. Besides, the enhanced electrical conductivity can effectively improve the reaction kinetics by synergistic effect of the binary metal oxides, as studied by density functional theory (DFT) calculations and storage mechanism studies. For lithium-ion batteries, the electrode exhibits an ultrahigh reversible capacity of 1141.7 mAh g−1, with an initial coulombic efficiency of 95.6%, and an ultralong life up to 800 cycles at 500 mA g−1. Even at a high current of 3.0 A g−1, a superior capacity of 484 mAh g−1 can be achieved. When using for sodium-ion battery anode, the reversible capacity is remained at 310 mAh g−1 after 100 cycles at 200 mA g−1, with a capacity retention of 90.4%. The electrode materials show long-term cycle stability and excellent rate capability, which gives a bright prospect for energy storage devices.

ReS2 has been considered as an emerging transition metal dichalcogenides (TMDs) material for sodium-ion batteries (SIBs). However, its electrochemical performance is severely limited by the structural aggregation and damage during deep charge-discharge. Here, a new 1D TiO2@ReS2 core-shell structure is reported for boosting the stable performance as the TiO2 has durable structural stability. The 1D TiO2 nanotubes with rough surface and large surface area are helpful to grow few-layer (≤4 layers) ReS2 nanosheets onto their surface. In the obtained 1D TiO2 [email protected]2 nanosheet (1D TiO2[email protected]2-NS) core-shell heterostructures, the exposed ultrathin ReS2 nanosheets offer high contact area for rapid Na+ diffusion, whilst the TiO2 nanotubes work as robust backbone for accommodating volume change and strain. Moreover, the chemical interfacial interaction between TiO2 and ReS2 gives rise to favorable synergistic effect, leading to enhanced electrical conductivity, Na+ diffusion kinetics, and structural stability at both electrode and materials levels. These findings can be supported by various characterization technologies such as X-ray photoelectron spectrum and high-resolution transmission electron microscopy. As a result, the 1D TiO2[email protected]2-NS electrode displays a desirable long-life span cycling performance of 118 mAh g−1 at 1 A g−1 after 1000 cycles in sodium-ion batteries. This work not only reports a stable SIBs anode material, but also provides fundamental understanding for designing and fabricating electrode materials for alkali metal ion batteries.

In this work MWNT/polypyrrole nanocomposites were synthesized and investigated as electrode materials for supercapasitor application. The MWNT were synthesized by CCVD-method and precipitated as buckypaper film (NTBP). The polypyrrole was precipitated on the NTBP surface by chemical (sample NTBP_PPy_Chem) and electrochemical (sample NTBP_PPy_Elect) polymerization. The morphology and functional composition of individual and hybrid materials were investigated by microscopic and spectroscopic methods. It was obtained that the deposition method and presence of NTBP affects the polymer morphology. It was shown that PPy chemical deposition leads to the precipitation of a large amount of an amorphous polymer on a buckypaper surface. At the same time electrochemical deposition method promotes the synthesis of uniform polymer layers. In the second case, the mass of the precipitated polymer is smaller. It was found that both deposition methods are suitable for the polypyrrole deposition and can increase the buckypaper capacity almost twice. The material long cycling showed that the NTBP_PPy_Elect sample has the greatest stability. Thus, in this study, the relationship between morphology, functional composition and electrochemical properties of materials was studied. It was shown that the synthesis method allows controlling the morphology and/or functional composition of the materials. Also it was demonstrated that the synthesized structures are promising for use as supercapacitor electrodes due to the high specific capacitance and stability.

In this paper, the SiO2-decorated graphite felts are obtained by silicic acid etching graphite felts in hot air, and their performance as the electrodes of iron-chromium redox flow battery (ICRFB) is investigated. The surface morphology, microstructure and surface chemical composition of SiO2-decorated graphite felts are characterized in detail through scanning electron microscopy, specific surface area analysis, X-ray Photoelectron Spectroscopy, X-ray diffraction, and Raman Spectroscopy. The electrocatalytic activity of SiO2-decorated graphite felts and the performance in ICRFBs are studied by electrochemical impedance spectroscopy, cyclic voltammetry, and single-cell charge-discharge cycling tests. Results indicate that the SiO2 introduced by the decomposition of silicic acid can increase the effective specific surface area of the graphite felts, and concurrently facilitate the oxidation of the SiO2-decorated graphite felts in hot air. The number of oxygen functional groups and the defect sites on the surface of the SiO2-decorated graphite felts increase to a great degree that especially have a considerable influence on the negative reaction activity of the ICRFB. An ICRFB assembled with graphite felts etched by 50 wt% silicic acid as the electrodes has a voltage efficiency and energy efficiency of 86.27% and 79.66% at a current density of 120 mA/cm2 respectively. The decay rate of capacity is only 0.46% per cycle. The cost-effective and convenient method demonstrated in this paper can coordinate the control of oxygen functional groups, surface area and electrical conductivity of graphite felts, which may provide an example for improving the electrode materials for the commercial application of ICRFBs.